Belief in God is rational.
Everything has a cause. So unless there is a first cause, then you would have an infinite regress. And then nothing could exist. Therefore there must be a first cause. Therefore God, the first cause, exists. QED. (You could prove the first step a priori that everything has a cause by noting that nothing can come from nothing. This makes it a priori, not just an empirical observation).

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25.1.17

Demonic synagogues. Do not judge a book by its cover. They might be raking in money by the barrel-full but that means nothing.[That is a theme that sometimes come up with Reb Nachman but his main point is that the teachers are bad. He usually does not focus on groups.] False friends and false teachers tend to be the problem. And when they are bold and fearless they are worse. False teachers have all the virtues. They have every good quality but truth.The Satan has all the gifts. They demonic synagogues will promise every type of good thing that they can in fact deliver, Parnasa money, shiduch [wife] but when payment time comes to pay, the toll is awful. There are no free gifts. It is at the cost of one's soul.There is pseudo Torah, phony Torah. Or as Reb Nachman called it תורה של הסטרא אחרא Torah of the Dark Side. This what the demonic synagogues teach and it makes money and has enormous success. People are not what they appear to be.While focusing on the negative I might as well mention the basic things that are Torah from the Bright and Holy Realm. The trouble is the Dark Side uses every means to seem to be kosher. What every kind of learning I could recommend they will jump at. [The only kind of places I would go to would be Reform or Conservative synagogues or Litvak yeshivas. The religious world is devoted to many forms of worship of the dead, and keep Torah in clothing and appearance alone.]